Telephone-exchange system



Sept. 2 1924. 1,506,884

W. W. CARPENTER TELEPH ONE EXCHANGE SYSTEM FiledJuly 11. 191 9 2 Sheets-Sheet 1 //1 1/6/7/0/1' War/en V14 Ca/peflfel Sejat. 2 1924. 1,506,884

V w. w. CARPENTER TELEPHONE EXCHANGE SYSTEM Fiied July 11. 1919 2 sum-sum. -2

/m/e/120r.' War/e W Ca/pemer.

Patented Sept. 2, 1924.

omen STATES WARREN N. CARPENTER, OF BROOKLYN, NEW YORK, iASSIQNQsR .TO WESTERN TRIC COMP-ANY, INCORPGRA'DED, OF NEW YORK, N. Y., A GQ R-PORATION OF NEW YORK.

. TELEPHONE-EXCHANGE SYSTEM.

A a i filed m a ie JN9--10 fi T v all whom it may conce n Be it known that I, \V REN W. CARPEN- rnu, a citizen of the United States, residing at Brooklyn, in the county of Kings, State of New York. have invented certain new and useful Improvements in Telephone-EX- change Systems, of which the following isra ful l,clear, concise, and exact description.

This invention relates to improvements in telephone-exchange systems and has particular reference to switching means therefor.

Broadly, the system of the present invention includes a plurality of subscribers lines served by a lesser number of link circuits, any one of which maybe seized upon the initiation of a call to interconnect a calling with-a called subscriber.

An object of the invention is to provide novel means whereby the calling and called lines are simultaneously connected to the seized link circuit upon the selection thereof.

Another object is the provision of an impulse controlling mechanism .common .to plurality of subscribers :lines and operable in response to the transmission of a setof impulses from the callingsubscribers substation to initially" actuate a set of counting relays included therein and then effect the selection of an idle link circuit,

The inventive idea involved is capable of receiving a variety of expressions one of which. for the purpose of illustrating the invention, is shown in the accompanying drawings; but it is to be expressly understood that said drawings are employed merely for the purpose of facilitating the description of the invention as a whole and not to define the limits thereof reference being had to the appended claims for this purpose.

In the drawings Figs. 1 and 2, with Fig. 2 below Fig. 1; illustrate diagrammatically the circuits employed in the present invention.

The invention is illustrated as applied :to a small private branch exchange containing seven subscribers. an attendants position and a central office trunk connection-although it will be understood that this arrangement may be varied without departing from the spirit or scope'of the invention. v I

Briefly stated, the system is preferably,

thoughnot necessarily, of a full relay type and provides for a'number of subscribers lines having access to a lesser number of link circuits, two of which are shown in 2. Each subscribers line extends through a number of normal'key contacts under the. control of theattendant and has associated therewith an individual relay mechanism which is operatedupon the initiation :of a call to seize an impulse :controlling mechanism common to the subscribers lines. The. seizure of this impulse controlling mechanism prevents the establishment ofanother call until the mechanism is again a number to the maximum number of iin pulses transmissible in any one series by .a

single operation of the .subscribers calling dial. At the termination of said series of impulses an idle link circuit is selected by a condition existent at the'controllingmech anismf Switching devices individual to the link circuit are then operated to simultaneously energize other switching devices preferablyin the form of junction relays and:

individual to the calling and called lines. where'upon the called subscriber s signalled and upon the removal of his rece ver from its .switchhook the connection is established Provision is also made for interconnectmg a subscriber wlthln the exchange and an attendant thereat, in which lnstance the subscriber sends nine impulses by dialing the digit 0 and the operation is then substantially the same as described in connection with the establishment of a call 'between two subscribers. An attendant may, -by the operation of certain keys at her position, connect her line toia central oflice .exchange and also connect a central off ce trunk to a subscribers substation. e 1 A su s ib 'm v @2111 a centra efii e 0pe d ec by d a g w e e pon the manually signal the called subscriber and connect the central office trunk to his line by the operation of certain keys at the attendants board. By providing an impulse sending device at the attendants position and a relay mechanism individual to the attendants line similar to the mechanism provided for each SHbSCIlbElQlt will be apparent that the attendant may automatically call a subscriber within the exchange or" a central office operator.

It is believed that the system will now be fully understood from the following detailed description of the operation in establishing various connections.

Let it first be assumed that the subscriber at substation A, whose number is 8, desires to converse with the subscriber at substation B, whose number is 2. Upon the removal of the receiver from its switchhook at. substation A, line relay 100 individual to the subscribers line is energized over a circuit extending from grounded battery, winding, back contact and inner right armature of relay 100, back contact and outer right armature of relay 101, right alternate contact of cutoff relay 102, the normal contacts of keys 103 and 104, the substation line loop, left alternate contacts of relays 105, 102, 106 and 107 to ground. Energization of line relay 100 establishes a circuit for relay 105 extending from grounded battery, right winding of relay 105, front contact and outer left armature of relay 100 to ground. Relay 108 is energized in parallel with relay 105 over a circuit. extending from grounded battery left winding of relay 108, front contact and outer left armature- 100 to ground. Attraction of the inner right armature of relay 100 closes a circuit for pulsing relay 100 of the impulse controlling mechanism common to all of the subscribers lines, which circuit extends from grounded battery, winding of relay 109, front contact and inner right armature of relay 100, back contact and outer right armature of relay 101, right alternate contact of relay 102, the subscribers line loop, left a ternate con tact and armature of relay 105 to ground through the dial tone apparatus DT. By the attraction of the outer right armature of relay 100. the energizing circuits for all other line relays individual to the other subscribers are opened, thus preventing said other subscribers from seizing the common impulse controlling mechanism until the line relay of the calling subscriber releases which occurs shortly after the calling subscribers dial has returned to normal. Relay 100, after becoming energized, is locked up over a circuit extending from groundedcalling line over the previously described circuit for relay 109. The calling subscriber upon hearing this dial tone may proceed to operate his impulse sending device in accordance with the digit of the wanted line which, as assumed, is No. 2.

Pulsing relay 109 responds to the interruptions in the line circuit and upon the first deenergization of said relay a circuit is established for slow-to-release relay 113 extending from grounded battery, winding of said'relay, right armature and alternate contact of relay 107, back contact and right armatureof relay 100 and right alternate contact of relay 106 to ground. Relays 107 and 113 being slow to release will remain energized during the transmission of impulses. Energization of relay 113 removes battery from the right armature thereof, and at its left armature closes a circuit for relay 112 extending from grounded battery. winding of said relay, front contact and left armature of relay 113, left armature and alternate contact of relay 107 to ground. Relay 112 energizes and locks up over the circuit extending from grounded battery, winding, front contact and left armature of said relay, left armature and alternate contact of relay 107 to ground Energization of relay 112 transfers the locking ground for relay 100 from the right alternate contact of relay 106 to the alternate contact and outermost right armature of relay 112. The first deenergization of pulsing relay 109 also establishes a circuit for relay 114 traceable from grounded battery, resistance 115,winding of relay 11 1, back contact and outer left armature of relay 116, left armature and back contact of relay 117, left armature and back contact of relay 109, left armature and alternate contact of relay 107 to ground. Relay 11% energizes and closes a circuit for counting relay 1, extending from grounded battery,

winding of relay 1, front contact and right armature of relay 114, the alternate contacts of all of the counting relays, left armature lay 107. Energization of relay 114 alsoenergizes relay 116 over a circuit extending from grounded battery resistance 115, Wind; ing, front contact and left armature of re lay 114, left winding of relay'116, left armature and. alternate contact of relay 107 to ground. Relays 114 and 116 lockup in this circuit and relay 109 is again'operated at the termination of the first impulse.

The second deenergization ofrelay109, in response to the interruption of: the line circuit establishes a circuiteXtending-from grounded battery, resistance ,115, "right armature and front contact of relay 116,

front contact and left armature of relay 116, left armature and back contact of relay 117, left armature and back contact of relay 109, left armature and'alternate con tact of relay 107' to ground. The current flowing over this circuit is diverted ffrom relay 114 so as to'short-circuit and cause the same to deenergize, but relay 116 remains energized over the circuit; extending from grounded battery, right winding of relay 116, frontcontact and left armature of said relay and from thence oyer the previously described circuit to ground at the relay'107. The second counting relay (not shown) which is similar in all respects to the succeeding counting relays is. now energized over the circuit which extends from grounded battery through the winding of the relay, outer left armature and front contact of counting relay 1, front 40 contact and left armature of relay 116 to ground at relay 107. Energization of the second counting relay breaks, at its alternate contact, the locking circuit for counting relay 1, which then deenergizes. The second counting relay then locks up through the alternate contacts of the succeeding re lays to ground at relay 107. The second operation of relay 109 at the termination of the second impulse causes relay 1.16 to re lease and also breaksthe circuit for slowto-release relay 113, which, after an inter-v val of time, deenergizes. SlOW-td-release relay 107 remains operated over its original energizing circuit. The foregoing operation is repeated should a calling subscriber 0perate his dial to send further impulses. Upon the release of relav 113, a circuit is established from grounded battery, back contact and right armature ofrelay 113, winding of relay 106, innermost right arina ture and front contact of relay 112, left armature and alternate contact of relay 107 to ground, and relay 106 becomes energized in this circuit. The holdingcirouit for relay 107 is then broken at the right armature-of relay 106fbut relay 107 does not release until aftera short interval.

Battery, now connectedto the right armature and back contact of relay 113, is also transmitted to relay 118, but ifthe called line is idle this relay will not operate. Relay 117 will, however, be energized over a circuit traceable from-grounded batter-y, back contact and right armature of relay 113,'right armature and back 'contact of relay 118, winding of relay 117, innermost right armature and front contact of relay 112, left armature and alternate contact of relay 107 to ground. Energization of relay- 11-7'closes a circuit for relay 101eXtending from grounded battery," right winding of I relay 101', alternate contact thereof, front contact and left armature ofrelay 100, front contact and outer'right armature of relay 117, back contact and outer left armature of relay 118, middle right armature and front contact of relay 112, left armature and alternate contact of relay 107'to ground. Relay 10.1 upon energizing will lock up through its alternate contact and inner right armature to the subscribers lineloop.

Assuming that the first link circuit shown in Fig. 2 is idle, relay 200 associated therewithwill be in normal position. and upon operation of relay 117, circuits will be closed in parallel for relays 201, 202, 203, extending from grounded batteryithrougli the windings,

of said relays, back contact and lower armature of relay 200, frontcontact and 'inner right armature of relay 117, back contact and outer left armature of relay 118, middle right armature and front contact of'relay 112, left armature and alternatecont'act of relay. 107 to ground. If the first link is busy, relay 200 will be energized and relays of the nextidle link similar to relays 201, 202 and 203 will be energized over the circuit extending through the front contact and lower armature of said relay 200. Energization of relay 202 closes a circuit for junction relay 204, individual to the calhng subscribers line, which circuit extends froni'grounded battery, left. winding of relay 204. lowermost armature and front contact of relay 202. con ductor 8 (Fig. front contact and inner left armatureof relay 100,front contact and outer right armature of relay 117. back contact and outer left armature of relay 118. middle rightarmature and front contact of relay 112, left armature and alternate contact of relay 107, toground. Simultaneously an energizing circuit is closed for junction relay 205 of the called subscribers line ex tending'from grounded battery, left wind-f ing of'relay 205, inner lower armature and front contact of relay 202, conductor '2, which extends through the front contact and middle left armature .ofthe'second counting relay which is now energized andlocked up, right armature and alternate contact of relay 106 to ground. The calling and called lines are now connected through the link circuit.

At the same time that junction relays 204 and 205 are energized, a circuit is also established for relay 206 extending from grounded battery, winding of said relay, armature and back contact of relay 208, inner upper armature of relay 201, conductor L, back contact and inner left armature of counting relay 1', right armature and alternate contact of relay 106 to ground. Relay 206 energizes and locks up over a circuit extending from grounded battery, winding of said relay, armature and back contact of relay 208, outer right armature and front contact of relay 206 to ground. Slow-torelease relay 207 is now energized over a circuit extending from grounded battery, winding of said relay, outer left armature and front contact of relay 206 to ground. Energization of the latter relay also provides a holding circuit for relay 105 extending from grounded battery,-left winding of relay 105, back contact and left armature of cutoff relay 102, outermost left armature and front contact of relay 204, innermost left armature and front contact of relay 206 to ground. It will be recalled that relay 101 has been energized and upon the energization of junction relay 204 and relay 207 a locking circuit is established for relay 204, which extends from grounded battery. front contact and left armature of relay 101, inner right armature and alternate contact of relay 105, conductor 119, right armature, front contact and winding of relay 204, left armature and front contact of relay 207 to ground. Relay 108 is also locked up in this circuit in series with relay 204. A locking circuit for junction relay 205 individual to the called subscribers line is also established, which circuit extends from grounded battery, winding of cutoff relay 102 individual to the called line, right alternate contact of relay 105, also in dividual to the called line, conductor 119, right armature, front contact and right winding of relay 205, left armature and front contact of relay 207 to ground. Relay 102 of the called line is energized in this circuit. The foregoing operation beginning with the breaking of the circuit of relay 107 by the energization of relay 106 takes place before relay 107 releases and upon deenergization thereof, the holding ground for relay 106 is removed, causing said relay to deenergize. The locking circuit for relay 112 is also broken whereupon the latter relay will release. Release of relay 107 removes the locking ground for the second counting relay which then releases. Relays and 111, which were locked up to ground through the alternate contact, and outermost right armature of relay 112 become deenergized when relay 112 is released. Deenergizaton of relay 100 breaks the circuit for relay 109 which 201 closes a circuit for relay 200 extending from grounded battery, upper winding of relay 200, back contact and uppermost armature of relay 201, front contact and right armature of relay 207 to ground. Relays 200 and 207 remain energized during the establishment of a call and the energization of re- I lay 200 causes the selection of the next idle link circuit. The impulse controlling mechanism common to all of the subscribers lines is nowagain in normal position and ready to be operated by the initiation of another call.

Upon the energization of relay 206, ringing current is applied to the called subscribers lineover a circuit extending from a suitable source of ringing current through the winding of marginal relay 208, front contact and right armature of relay 206, front contact and middle left armature of relay 205, the called subscribers line loop including the ringer apparatus, outer left armature and front contact of relay 205, inner right armature and front contact of relay 206 to ground. Ringing tone is also applied to the calling subscribers line through relay 208, front contact and right armature of relay 206, front contact and middle left armature of relay 204, winding of relay 121, right armature and back contact of relay 102, condenser 145 and left winding of relay 101 to ground, then by induction from the leftwinding of relay 101 into the right winding thereof, the alternate contact and inner right armature of relay 101, right alternate con tact of relay 102, the subscribers line loop, left alternate contact and armature of relay to ground. If the called subscriber answers, the removal of his receiver from its switchhook will cause sufficient current to flow through relay 208 to energize same, whereupon the locking circuit of relay 206 is broken and the same releases. Removal of ground from inner left armature and front.

105, conductor 119, right armature, fr t contact and right winding of relay 204, left armature and front contact of relay 207 to ground. Relay 102 attracts its armatures and connects the calling subscribers line to the link circuit and called subscriber lines. Relay 121 is then operated in series with the calling subscribers line loop and will establish another holding circuit for relay 207 before the same can release which circuit extends from grounded battery, winding of relay 207, front contact and innermost left armature of relay 201, front contact and armature of relay 121, left armature and front contact of relay 108 to ground. At the time cutoff relay 102 of the'calling sub: scribers line is operated the locking circuit for relay 101 extending through right alternate contact and inner right armature thereof, and from thence over the subscribers line loop is broken and relay 101 releases. Conversation between the calling and called subscribers may now proceed.

If the called line is busy, relay 118 will operate over a circuit extending from grounded battery, back contact and right armature of relay 113, winding of relay 118, lowermost armatures and back contacts of relays 203 and 203, innermost-left armature and front contact of the second counting relay, which has become energized, thence over a conductor similar to the one leading to the front contact andinnermost left armature of counting relay 8, said conductor extending to the relay mechanism individual to the called subscribers line, conductor 119, also individual to the called line, right armature, front contact and right winding of relay 205, left arr iature and front contact of relay 207 to ground. Energization of relay 11S prevents relay 117 from being operated and closes a circuit for relay 101 of the calling line which circuit eX- tends from grounded battery, right windscriber's loop, left alternate contact and left armature of relay 105 to ground. As previously described, upon the release of relay 107, the entire impulse controlling mechanism returns to normal including relay 118, which was locked up through its winding, front contact and inner left armature and the middle armature and front contact of relay 112 to ground at relay 1071' Release of relay 112 causes the deenergization of relay which breaks the holding circuit for relay and causes the latter to release. The locking ground for relay 101 is then transferred from the left armature of'relay 105 to the left alternate contact of said re 1 y, left alternate contactsof relays 102,106

the same and 107. Release of relay 1.05 applies a busy tone to thecalhng subscribers line extendmg from ground through the busy tone apparatus BZ, outer rlght armature andback contact of relay 105, right winding of relay 101 to grounded battery. This busy tone is transmitted through the"alternbfecontact' and inner left armature of relay'101 to the subscribers lineyloop. l Y

Upon hearin this busy tone, the calling subscriber replaces his receiver upon. its

s\\=.tc'l1hook, and thereby breaks the locking I circuit for relay 101' which then -:releases. At the tune relay 100 became deenergizech the holding circuit for relay 108 is also broken at the outer left armature and front l per armature of relay 200 to the first link circuit. upper armature andfront contact'of I relay 200 individualto the second link cir- (11111 the upper armatures. and front contacts of the individual relays of all other link cirof relay 113 to: grounded battery} Energization of relay 118, establishes an enera'izmg circuit for relay ,101 and applies.

busy tone to the calling subscriberslineras previously described." "Upon hearing the.

receiver upon its switchho'ok and causes the relay 101 to-deenergize. s Relay 118 remains energized until one of thelink circuitslbecomes idle, at which time the associated individual relay similar to relay 200 will deenergize and cause the releaseof relayi118.

At the termination of thelconversationz in the event of a successful establishment-of a call the calling subscriber, by yrepla'ci his receiver upon its switchhook, causes the relay 121 to release. This breaks the circuit for relay 207 which extended throiuihthefront contact and armature of relay 121, to

ground at the left armature of relay 10S'and relay 207 then releases. Removal of ground tion of another cal,

To call an attendant from a subscribers substation, the operation of the impulse contrcling mechanism and the switching'devices individual to the seized link circuit is described in connection with the call between two subscribers, with the following exceptions.

After the'calling subscriber has removed 100 bug-V tone? e calling subscriber replaces his' his receiver from its switchhook and hears the dial tone, the impulse sending device at the substation is operated to transmit nine impulses to energize and lock up counting relay 0. Assuming that the first link circuit and the attendants position is idle, a circuit will be established for relay 210 extending from grounded battery, winding of said relay, inner upper armature and front contact of relay 202, conductor 0, front contact and outer left armature of counting relay 0, right armature and alternate contact of relay 106. to ground. The operation of relay 210 joins adjacent ends of two permanently paired link circuits to form a loop circuit for connecting the operators telephone line to the calling subscribers line. Relay 210 locks up through its winding, front contact and lower armature to ground at the left armature and front contact of relay 207. A circuit is then completed for a ring-down drop relay (not shown) at the attendants position to indicate a call from a subscriber, and theattendant at said position operates a key to shift contacts 141. A circuit is now closed from the subscribers substation, through the armatures of cutoff relay 102, two outer left armatures and front contacts of junction relay 204, the upper armatures and front contacts of relay 210, contacts 141, to the attendants telephone. The battery key including contacts 135 and 136 may be operated by the attendant to furnish talking current to the attendants line from relay 211.

If the attendant is busy when the call from the subscriber is initiated. relay 118 will be energized over a circuit extending through the inner left armature and front contact of counting relay 0 and over the conductor S0, to a ground (not shown) at the attendants position. Energization of relay 118 will produce the same results as previously described and a'busy tone will be applied to the calling subscribcrs line.

Should a subscriber desire a connection to a central ofiice operator, the call is initiated by the removal of the receiver from its switchhook which energizes line relay 100, as previously described and upon energiza tion of relay 105, the dial tone is applied to the calling line. The sending device of the calling subscriber is operated to send one impulse which will cause counting relay 1 to energize and lockup, as previously set forth. At the termination of the single impulse, relay 109 remains energized and causes the release of relay 113. This closes the aforementioned circuit for relay 117 providing there is an idle centralofiice trunk. Relay 106 is also energized by the release of relay 113. Relays 201, 202 and 203 are then energized in parallel through the back con-- tact and lower armature of relay 200 to ground at left armature and alternate contact of relay 1.0T. Counting relay 1, being locked up to ground at the left alternate contact of relay 10 7, will not deenergize until said relay 107 releases and upon energization of relay 201, an energizing circuit will be established for relay 209 extending from grounded battery, winding of relay 209,

lowerarmature and front contact of relay 201., conductor T, front contact and inner left armatureof relay 1, right armature and alternate contact of relay 106 to ground. Energization of relay 117 also establishes the previously described energizing and. locking circuits for relay 101. Energization of relay 209 closes a circuit for relay 0 204 extending from grounded battery, w1nding of relay 207, outer left armature and front contact of relay 209 to ground. Energization of relay 207 connects ground to the left armature thereof and thereby closes the lockingrircuit for relays 108 and 204 as previously described. \Vhenrelay 106 is energized, the holding ground for relay 107 is removed and this relay, after an interval, releases and causes relay 112 to deenergize. The release of relay 107 breaks a circuit for relay 106, but this relay being slow to re lease, does not deenergize at this time. Helease of relay 112 causes relay 100 to deenergize, which, in turn, breaks the energizing circuit for relay 10?. Before relay 106 can release, the following action takes place: Upon the release of relay 105, a. circuit is established for cutoff relay 102 extending from grounded battery, winding of relay 102, right alternate contact of relay 1055, conductor 119, right armature, front contact and right winding of relay 204, left armature and front contact of relay 207 to ground. Cutoff relay 102, energizing, ex-

tends the calling subscribers line and closes I a circuit for line relay 122 extending from grounded battery, right winding of relay 122, left alternate contact of cutoff relay 123, front contact and inner left armature of relay 209, back contact and inner left armature of relay 206, front contact and outermost left armature of relay 204, left armature and alternate contact of cutoff relay 102, the sub-v scribers line loop, alternate contact and right armature of relay 102, winding of relay 121, middle left armature and front con-' tact of relay 204, right armature and back contact of relay 206, inner right armature and front contact of relay 209, right alternate contact of relay and left winding of Relay 122, upon energizing, es- 1 gizes and establishes .a locking circuit for relay 209 extending from grounded battery, winding, outer right armature and front contact of relay 209, left armature andfront contact of relay 124. to ground. As soon as andremains in this condition until the call is terminated, thereby extending another call .to the next idle link circuit.

At the time of the energization' of relay 122, a circuit is established for line relay 126 at the central ofiice operator s position which circuit extends from grounded battery, left Winding of relay 126, outer armature and back contact of cutoff relay 127, front contact and right armature of relay 122 and alternate contact of slow-toa'eleajse relay 128 to ground. -Relay 126 energizes and operates the signaling lamp at the cen tral office operators position to indicate an incoming call onthe trunk with which said lamp is associated. The central oflicefloperatdr'thenfplugs into the jack and thereby operates the cutoff relay 127 in the usual manner to extinguish the lamp. Byplugging in, a circuit is also closed for relay 129 Which is bridged across the line and said relay energizes A circuit is then established for relay 128 extending from grounded battery, winding of said relay,front contact andarmature of relay 129 to ground. Relay 128 then energizes and closes a circuit for cutoff relay 123 which circuit is traceable from grounded battery, winding of relay 123, front contact and right armature of relay 124 whichhas already been'energized, rightarmature .and alternate contact of relay 1 28 to ground. Energization of relay 123 breaks the circuit for line relay 122, but relay 12 1 which was originally energized by the ground at the left armature' of relay 122,

s does not release due to the ground at the front contactand outer left armature of relay 123. Energization of the latter relay also extends the calling line to the central ofii'ceoperatofls position and indoing so energizes relay 130. Relay 131 is then energized over a circuit extending from grounded battery, winding of relay 131, front contact and left armature of relay 1 10 to ground. Relay 131, by attracting'it left armature, breaks the energizingcircnit for any 129.. which then releases- Be ar12 is then energized by. shag-mand in ight armature and front contact-of relay 130. Conversation may now proceed between the calling vsubscriber and the centraloffice operator through the resistance 132..

At the termination of the ,call,the calling subscriber, by replacing his receiver, deenergizes the relay 121, which causes'the restoration 1ofthe relay mechanism associated With the seized link circuit with the exception of relay 209, in the same manner as dcscribed in connection with the release of v said mechanism at the termination of a call betwefin. twosubscriberfs within the exchange.

lvhen the calling subscriber replaces his receiver, the energizing circuit for relay 130 is also broken and this relay releases, causing the deener'gizat-ion of relays 128 and 131.

Release of'relay 128 breaks the circuit for cutoli relay 123 which then restores and in.

turn causes the release of relay 124. The locking circuit for relay 209 is then broken at the left armature and front contact of relay 124, and the mechanisms associated with the link and central ofiice trunk cir cuits are then-in normal'positions. At the time oft-he replacing of the receiver upon its .switchhook at the calling substation, a suitable signal (not shown) at the central .oflice operators position is operated to indicate the termination of the call and the operator may then remove the plug from its ac I Qn an incoming call from the central oifice to one of the subscribers within the exchange, a call is first extended to an attendants position at the exchange. The central ,oflice opei atonby plugging into the jack, operates relay 129 which closes the previously mentioned energizing circuit for relay 128. This relay, upon energizing, closes a circuit for; relay 133 individualto the trunk leading to the 'at-tcndants position i'vhich circuit extends frorn grounded battony, winding of relay 133, left armature and from contact of relay 128 to ground. At the time the operator plugs in, she may operate her ringing key which will energize relay 130 to ground through the condenser 1&3 with the results to be later described.

Energization of relay 133 operates asignal 122 left alternate contact of relay 123.,con-

tact 135, battery key, tl elett'key contact 1 4 in its err-rat pea e l k y tacts, of the other attendants-keys,in their normal position, the atten dants line loop, ight key conta ts o s sle e k y right key e n-tac let s prat drq ien, y ccnt t 1.3. righ alternateeonta Qjf -re' ay- 123 and left winding of relay '122'to ground. Operation of relay 1.22 closes a circuit at its left armature for relay 124. Relay 125 is then energized and applies ground to its armature which closes an energizing circuit for relay 200 so that the associated link and central oilice circuits cannot be seized. Re-

lay 123 isnow energized over the previously described circuit to ground through the right armature of relay 128. Relay 123, by energizing breaks a circuit for relay 122 and provides a holding ground for relay 124. At the time relay 130 is operated, relay 131'is energized and breaks the circuit For relay 129; Relay 130 in operating, also provides a holding ground for relay 128. The attendant may now converse with the central office operator and upon determining the wanted subscriber may operate the holding key 137 to hold the central ofiice connection. Assumingfthat the subscriber A is wanted, the attendant then operates key contacts 138 of the key 104 and connects a source of ringing current to the subscribers line, which extends from the ringing current generator 139, right key contact 1 38, the subscribers line loop and left key contact 138 to ground. When the subscriber answers, the attendant restores the contacts 138 to normal and operates contacts 140 to connect the subscribers line loop to the trunk circuit, whereupon contacts 134 of the holding key 137 may be restored and conversation may proceed between the calling and called subscribers. At the termination of the call, mechanism associated with the central office trunk circuit is returned to normal in the same manner as previously described and the attendant, upon receiving a suitable signal, may restore the operated contacts 140, whereupon the parts are again in normal position.

A subscriber may be connected to central ofiice through an attendant instead of direct as previously described in which event the subscriber will first call the attendant by operating counting relay 0', and after the establishment of the connection the subscriber may then replace his receiver. The attendant then operates the key contacts 134, whereupon a circuit is established for line relay 122 with the same results as described in connection with a call direct from a subscriber to the central ofiice. Upon obtaining the connection to the central office operator the attendant may operate the holding key 137 and then ring the subscriber as previous ly set forth. When the subscriber responds the attendant operates key contacts 140 and connects the central ofiice trunk direct to the subscribers line. When the contacts 140 are operated, a circuitis closed for the cut-off relay 102 individual to the calling subscrib ers line which circuit is traceable from grounded battery, winding of relay 102,

right alternate contact of relay 105, contact 142, and left winding of relay 125, to ground. At the time relay 125 is energized, a circuit is established for relay 200 extending from grounded battery, upper winding of relay 200, back, contact and uppermost armature of relay 201, left armature and front contact of relay 125, to ground.

Energization of relay 200 indicates a busy condition of the particular link and trunk controlling mechanism to which said calling line is extended and'which is common to said lines, relays simultaneously actuated by said impulse cont-rolling mechanism for connect-- ing said calling line to said called line, and means under the sole control of the calling subscriber for releasing the established con nection.

2. In a telephone exchange system, calling and called subscribers lines, a relay mechanism individual to the calling line, a link circuit for joining said calling and called lines, an impulse controlling mechanism, switching means individual to said calling and called lines for connecting thesame to said link circuit, the operation of the switch ing means individual to the calling line being dependent upon certain electrical conditions at the relay mechanism individual to said calling line and at'said impulse: controlling mechanism, and the means individual to said called line being responsive only to an electrical condition-at the impulse controlling mechanism, and means for operating the switching means individual to said calling'and called lines.

3. In a telephone exchange system, calling and called subscribers lines, a relay mechanism individual to the calling line, alink circuit for joining said calling-and called lines, an impulse controlling mechanism, switching means individual to said calling and called lines for connecting the same :to said link circuit, the operation'of the switching means individual to the calling line beswitching ing dependent upon certain electrical condiof said impulse controlling mechanism for operating the'switching means individual to said calling and calledlines. g

4, In a telephone'exchange system, calling and called subscribers lines, a relay mechanism individual to the calling line. a link circuit for joining said calling and called lines, an impulse controlling mechanism in cluding a set of counting relays, means for energizing one of said counting relays, switching means individual to said calling and called lines for connecting the same to said link circuit, the operation of the switching means individual to the calling line being dependent upon certain electrical con-,

called lines, an impulse controlling mechanism including a set of countmg relays,

meanssfor energizing one of said counting relays, switching means individual to said calling and called lines for connecting the same to said link circuit, the operation of the switching vmeans individual to the calling line being dependent upon certain electrical conditions at the relay mechanism individual to said calling line and at said impulse controlling mechanism, and the switching means individual to said called line being responsive only to the energization of said counting relay and electromagneticmeans under the control of said impulse controlling mechanism for simultaneously operating the switching meansindividual to said calling and called lines.

6. In a telephone exchange system, calling and called subscribers lines, a line relay in.-

divid ual to the calling line,a link circuit for joining said calling and called lines, an

impulse controlling mechanism including a set of counting relays, means for energizing one of sald counting relays, unction relays individual to said calling and called lines torconnecting the same to said link circuit,

the operation of the junction relay individual to the calling line being dependent upon the energiz'ation of said line relay and upon an electrical condition atsaid impulse controlling mechanism, and'the junction relay individual to said called line being dependent upon the energization of said counting relay and means under the control of said impulse controlling mechanism for simultaneously operating said junction relays.

'7. In a telephone exchange system, a calling and'acalled subscribers line, means individual to said calling line for extending same, an impulse controlling mechanism to which said calling line is extended and which'is common'to said lines, and relays actuated simultaneously for connecting said calling line to said called line, one of said relays being individual to the calling line a),

and controlled by said impulse controlling mechanism and said individual means, and

the other relay being individual to the called line and controlled only by said impulse controlling mechanism.

In witness whereof, I hereunto subscribe my name this 9th day of July, A. D. 1919.

WARRENW. CARPENTER.

DISCLAIMER.

l,506,884.-Warren. W. Carpenter, Brooklyn, N. Y. TELEPHONE-EXCHANGE SYS- TEMS. Patent dated September 2, 1921. Disclaimer filed January 11, 1.926, by the patentee, assignee, lV'estern E Zectm'c Company, Incorporated, consenting. Hereby enters this disclaimer to the said claims of said Letters Patent which are in the following words, to wit: v e

1. In a telephone exchange system, a calling and a called subscribers line, means for extending said calling line, an impulse controlling mechanism to which said calling line is extended and which is common to said lines, relays simultaneously actuated by said impulse controlling mechanism for connecting said calling line to said ca'lled line, and means under the sole control of the calling subscriber for releasing the established connection.

2. In a telephone exchange system, calling and called subscribers lines, a relay mechanism individual to the calling line, a link circuit for joining said calling and called lines, an impulse controlling mechanism, switching means individual to said calling and called lines for connecting the same to said link circuit, the operation of the. switching means individual to the calling line being dependent upon certain electrical conditions at the, relay mechanism individual; to said calling line and at said impulse controlling mechanism, and the switching means individual to said called line being responsive only to an electrical condition at the impulse controlling mechanism, and means for operating the switching means individual to said calling and called lines.

3. In a telephone exchange system, calling and called subscribers lines, a relay mechanism individual to the calling line, a link circuit for joining said calling and called lines, an impulse controlling mechanism, switching means individual to said calling and called lines for connecting the same to said link circuit, the operation of the switching means individual to the calling line being dependent upon certain electrical conditions at. the relay mechanism individual to said calling line and at said impulse controlling mechanism, and the switching meansindividual to said called line being responsive only to an electrical condition at the impulse controlling mechanism, and an electromagnetic means under the control of said impulse controlling mechanism for operating the switching means individual to said calling and called lines.

7. In a telephone exchange system, a calling and a called subscribefis line, means individual to said calling line for extending same, an impulse controlling mechanism to which said calling line is extended and which is common to said lines, and relays actuated simultaneously for connecting said calling line to said called line, one of said relays being individual to the calling line and controlled by said impulse cont-rolling mechanism and said individual means, and the other relav being individual to the called line and controlled only by said impulse controlling mechanism.

[Ofiicz'al Gazette Febmm z 2, 1926.]

DISOLAI M ER. 1,506,8S4.--Wamen W. Carpenter, Brooklyn, N. Y. TELEPHONE-EXCHANGE SYS- TEM. Patent dated September 2, 1924. Disclaimer filed April 4t, 1928, by the assignee, Westevm'li'lectm'c Company, Incorporated.

Hereby enters this disclaimer to that part of the claims in said specification which are in the following words to wit:

1. In a'telephone exchange system, a calling and a called subscribers line, means for extending said calling line, an impulse controlling mechanism to which said calling line is extended and which is common to said lines, relays simultaneously actuated by said impulse controlling mechanism for connecting said calling line to said called line, and means under the sole control of the calling subscriber for releasing the established connection.

2. In a telephone exchange system, calling and called subscribers lines, a relay mechanism individual to the calling line, a link circuit for joining'said calling and called lines, an impulse controlling mechanism, switching means individual to said calling and called lines for connecting the same to said link circuit.

the operation of the switching means individual to the calling line being dependent upon certain electrical conditions at the relay mechanism individual to said calling line and at said impulse controlling mechanism, and the switching means individual to said called line being responsive only to an electrical condition at the impulse controlling mechanism, and means for operating the switching means individual to said calling and called lines. I

3. In a telephone exchange system, calling and called subscribers lines. a relay mechanism individual to the calling line, a link circuit for joining said calling and called lines, an impulse controlling mechanism, switching means individual to said callin and called lines for connecting the same to'said link circuit, the operation of the switching means individual to the calling line being dependent upon certain electrical conditions at the relay mechanism individual to said calling line and at said impulse controlling mechanism, and the switching means individual to said called line being responsive only to an electrical condition at the impulse controlling mechanism, and an electromagnetic means under the control of said impulse controlling mechanism for operating the switching means individual to said calling and called lines.

7 In a telephone exchange system, a calling and a called subscribers line, means individual to said calling line for extending same, an impulse controlling mechanism to which said calling line is extended and which is common to said lines, and relays actuated simultaneously for connecting said calling line to said called line, one of said relays being individual to the calling line and controlled by said impulse controlling mechanism and said individual means, and the other relay being individual to the called line and'controlled only by said impulse controlling mechanism.

[Qfiioia l Gazette Illay 1, 1.928.] 

